Accession Number:

AD0600848

Title:

INTERNAL FRACTION OF MARTENSITE.

Descriptive Note:

Annual technical rept. no. 1,

Corporate Author:

WALES UNIV CARDIFF

Personal Author(s):

• Rawlings,R.
• McGrath,J.

Report Date:

1964-02-29

Pagination or Media Count:

55.0

Abstract:

A survey of the literature dealing with the internal friction of martensite was made. The internal friction peak at 250 - 270 C, generally accepted as being due to stress-induced movement of dislocations associated with carbon atoms or carbide particles, increases in height with carbon content. The rate of increase with carbon content decreases when the C is more than about 0.6. Possible reasons for this are discussed - these include the increased proportion of austenite, the faster rate of tempering during the test and the possibility of saturation of the dislocations with the higher carbon contents. An inverted torsion pendulum using wire speciments 2.5in. long and 0.031 or 0.039in. dia., which may be either cooled below room temperature or heated either in vacuo or in a controlled atmosphere is described. Provision is made for the application of a d.c. magnetic field of about 250 oe. to the specimen in order to avoid magneto-elastic effects. These have been shown to be significant as shown by the decreased damping obtained by the use of a magnetic field. All testing was therefore carried out with a field which probably saturates the specimen magnetically. Author

Descriptors:

• INTERNAL FRICTION
• MARTENSITE
• STEEL
• DAMPING
• CARBON
• METALLURGY
• PHASE STUDIES

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE